1. Field of the Invention
The present invention relates to an image scanning device with a time authentication requesting function of a digital Multi Function Peripheral (MFP) or the like which assigns a timestamp to a document image scanned by a scanner and stores the document image assigned with the timestamp.
2. Description of the Related Art
Recently, a digital MFP including a copier function, a facsimile function, a printer function, and a scanner function or the like assigns a timestamp to a document image scanned by a scanner, and stores the document image as an e-document. That is, since digital data can be easily altered compared with a paper document, timestamp technology has been used. The timestamp is technology for certifying time when an electronic document has been fixed. The timestamp certifies from when such a document has been existing, and a fact that the document has not been altered by third parties and also a creator himself from the time when the document was created.
When adopting such timestamp technology, first, a device transmits a hash value of an electronic document to a Time Stamping Authority (TSA). The TSA encodes the hash value and information of correct time clocked by an electronic clock, and returns to the device as a timestamp. The device saves the received timestamp along with the electronic document.
When verifying such an e-document, the device decodes the timestamp, and confirms the time information of the timestamp. Then, the device compares the hash value of the electronic document, which has been separately calculated, with the hash value included in the timestamp. Accordingly, verification can be carried out as to whether or not the e-document had been altered. Further, the hash value is a fixed length value generated using a one-way function (hash function) that is irreversible from a given original text. The hash value is also known as a message digest, etc. Since it is extremely difficult to obtain the original text from the hash value and to create different documents having the same hash value, it is possible to confirm whether or not the original text is identical by comparing the hash values.
As described above, the conventional digital MFP can store the scanned document along with the timestamp as an e-document. However, since costs are required for requesting the timestamp, a large amount of costs would be required to provide all documents in a form of e-documents. Meanwhile, when one wishes to destroy a paper document, although such a document may not be required to be converted into an e-document at such time, the document may be required to be converted into an e-document at a later date. Accordingly, the document could not be destroyed after all, and a large volume of documents were required to be kept.